This invention relates, in general, to etching semiconductor materials, and more specifically to etching vertical cavity surface emitting lasers.
Conventional edge emitting semiconductor lasers are playing a significant role in development of optical communications due to their high operating efficiency, small size and modulation capabilities. However, with increasing performance needs, further reduction in size, and greater manufacturing needs, these devices have been experiencing limitations.
Recently, there has been an increased interest in a new type of laser device called a vertical cavity surface emitting laser (VCSEL). Advantages of VCSEL devices are that the device is smaller, has potentially higher performance, and is potentially more manufacturable. These advantages are due in part from advances in epitaxial deposition techniques such as metal organic vapor phase epitaxy (MOVPE) and molecular beam epitaxy (MBE). However, even with advances in material deposition, problems still occur with performance due to etching of epitaxially deposited materials.
Conventional etching of these materials is achieved in customized plasma reactors with chlorine gas chemistries. Etching with customized reactors and chlorine gas chemistries have yielded devices that have poor performance due to several reasons such as surface damage, poor anisotropy, unstable etch conditions, or the like. Many of these problems are discussed in a paper by A. Scherer, et al, "Fabrication of Microlasers and Microresonator Optical Switches," Applied Physics Letters, December 1989, pages 2724-2726.
It can be seen that use of conventional etching techniques do not meet requirements that are necessary to manufacture sensitive semiconductor devices such as VCSEL's. Therefore, a method for etching sensitive devices by use of common plasma reactors, that would improve etching characteristics and performance of these sensitive devices would be highly desirable.